|Publication number||US5462000 A|
|Application number||US 08/360,475|
|Publication date||Oct 31, 1995|
|Filing date||Dec 21, 1994|
|Priority date||Dec 21, 1994|
|Publication number||08360475, 360475, US 5462000 A, US 5462000A, US-A-5462000, US5462000 A, US5462000A|
|Inventors||William H. Nedderman, Jr., Robert Meunier|
|Original Assignee||The United States Of America As Represented By The Secretary Of The Navy|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (3), Referenced by (2), Classifications (9), Legal Events (4)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.
(1) Field of the Invention
This invention relates generally to retractable hook eyes and more particularly to a retractable pull-down eye for use in hauling a buoyant test vehicle (BTV) down to a release depth below a water surface. The eye is spring loaded to retract into the tail housing of the BTV when released and is shaped to conform to the contour of the tail section of the BTV to minimize turbulence. Channels within the eye or other means are provided to allow water to escape as the eye retracts into its housing. A tapped hole is provided in the eye to extend the eye when attaching the pull-down hook.
(2) Description of the Prior Art
BTV systems are used to test noise generated by shapes moving through a fluid medium. The BTV is configured to conform to the desired shape, hauled down below the water surface and released. Noise measurements are taken as the BTV rises to the surface. Current BTV's use a pull-down eye attached to the tail piece of the BTV together with a well known Benthos acoustic deep sea release. A cable is attached to the eye and the BTV is pulled below the surface. When the desired depth is reached, an acoustic signal is transmitted to the Benthos release which causes the hook on the Benthos release device to open allowing the BTV to ascend. The pull-down eye attached to the ascending BTV generates extraneous noise not corresponding to the shape being tested. To eliminate the extraneous noise, a non-turbulent pull-down eye is required. Further, the pull-down eye must be non-turbulent almost immediately upon release, such that noise measurements will not be adversely impacted.
Lovejoy in U.S. Pat. No. 4,331,096 discloses a retractable pad-eye device having a shape corresponding to the surrounding structure when in its retracted position. However, the device requires a manual operation to change between the pad-eye and the retracted positions. Such a device cannot be used with a self-releasing BTV at substantial depth below the water surface. Spring loaded pad-eyes or cleats are well known in the art. Such devices, as disclosed by Morris in U.S. Pat. No. 4,890,566 and Harris in U.S. Pat. No. 5,004,388, typically provide for the spring action to extend the cleat upon release, rather than retract. No current devices provide the non-turbulent shape combined with the quick retraction required for sensitive noise measurements.
Accordingly, it is a general purpose and object of the present invention to provide a pull-down eye for a BTV having a non-turbulent shape to minimize extraneous noise during BTV noise generation testing.
It is another object of the invention to have the pull-down eye automatically assume the non-turbulent configuration when the BTV is released.
Yet another object of the invention is to have the pull-down eye quickly retract from an extended position to the non-turbulent configuration.
A further object of the invention is to minimize noise during retraction.
A still further object is to provide means to extend the eye from the retracted position.
These objects are accomplished with the present invention by providing a pull-down eye assembly in the tail housing of a BTV. The shape of the pull-down eye assembly conforms to the general shape of the BTV tail housing such that the pull-down eye assembly does not create any additional turbulence while the BTV moves through the water. The pull-down eye is extended from the tail housing when the BTV is to be hauled down to the release depth. A cable is attached to the pull-down eye and the BTV is winched down to the test depth. The pull-down eye is spring loaded to automatically and quickly retract back to the non-turbulent configuration when released. Channels within the eye or other means are provided to allow water to escape from the housing as the eye retracts back into the tail housing. Resilient pads are provided between the pull-down eye assembly and the tail housing to eliminate any metal to metal contact noise as the pull-down eye comes to rest against the tail housing. During the BTV ascent test stage, the pull-down eye remains in the non-turbulent configuration. To prepare the BTV for another test ascent, the pull-down eye is extended by means of a tapped hole and the cable is re-attached.
A more complete understanding of the invention and many of the attendant advantages thereto will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein corresponding reference characters indicate corresponding parts throughout the several views of the drawings and wherein:
FIG. 1 shows a BTV with the pull-down eye extended being hauled down to test depth;
FIG. 2 shows a partial view of a tail housing of a BTV with the pull-down eye extended;
FIG. 3 shows a partial view of a tail housing of a BTV with the pull-down eye retracted;
FIG. 4 shows a sectional view of a preferred embodiment of the pull-down eye assembly parallel to the plane of the pull-down eye with the pull-down eye extended from the tail housing of the BTV; and
FIG. 5 shows a sectional view of an alternate embodiment of the pull-down eye assembly parallel to the plane of the pull-down eye with the pull-down eye extended from the tail housing of the BTV.
Referring now to FIG. 1, there is shown BTV 10 being hauled down to test depth by cable 12. Cable 12 is attached to BTV 10 by means of Benthos release device 14 hooked to pull-down eye assembly 100. Referring now additionally to FIG. 2, there is shown a partial view of BTV 10 in the haul down phase with pull-down eye assembly 100 extended from tail housing 16 of BTV 10. Tail housing 16 has a slot 18 to accept pull-down eye assembly 100. Benthos release device 14 attaches to pull-down eye assembly 100 through eye aperture 102. BTV 10 is positively buoyant and thus assumes a vertical position during haul down. FIG. 1 shows cable 12 attached to a winch (not shown) via float 20. When the proper test depth is reached, an acoustic signal is transmitted to Benthos release device 14 causing it to release pull-down eye assembly 100.
Referring now to FIG. 3, there is shown a partial view of BTV 10 in the ascent stage after BTV 10 has been released. Pull-down eye assembly 100 is retracted into tail housing 16 with exposed surface 104 of pull-down eye assembly 100 conforming to the general shape of tail housing 16.
Referring now to FIG. 4, there is shown a cross-sectional view of tail housing 16 with pull-down eye assembly 100 shown therein. Assembly 100 is shown partially extended from tail housing 16. Exposed surface 104 is seen to conform to the generally cone-shaped tail housing 16 and to lie along conical axis X--X. In the preferred embodiment of FIG. 4, assembly 100 is fabricated from flat stock having and eye end 106, a middle portion 108 and a forward end 110. Eye end 106 comprises eye aperture 102 and exposed surface 104. Eye end 106 is wider than middle portion 108, forming faces 112a and 112b, symmetric about axis X--X. When retracted, faces 112a and 112b rest against base 22 of slot 18. At forward end 110, the flat stock is rounded to form threaded shaft 114. Retainer ring 116 fits onto shaft 114 and nut 118 is threaded onto shaft 114 to secure retainer ring 116 onto shaft 114. Middle portion 108 and forward end 110 fit within a series of coaxial bores, 24, 26 and 28, within tail housing 16. First bore 24 has a threaded end 24a for attaching tail housing 16 to BTV 10 (not shown). The other end forms stop 24b. Second bore 26 has a smaller diameter than first bore 24 and extends from stop 24b further into tail housing 16 along axis X--X ending at shoulder 26a. Third bore 28 has a diameter smaller than second bore 26 and slightly larger than middle portion 108. Third bore 28 extends from shoulder 26a to intersect slot 18. Spring 120 surrounds middle portion 108 and extends between shoulder 26a and retainer ring 116. Retainer ring 116 is slightly smaller in diameter than bore 24 allowing movement of assembly 100 along axis X--X. As eye end 106 is extended away from tail housing 16, spring 120 is compressed between retainer ring 116 and shoulder 26a until retainer ring 116 rests against stop 24b. A small threaded bore 122 is provided in exposed surface 104 aligned with axis X--X for use in pulling eye end 106 away from tail housing 16 after having been retracted flush with tail housing 16. A further bore 124 is provided through eye end 106, perpendicular to the plane of assembly 100 and spaced slightly apart from eye aperture 102 in the direction of middle portion 108. Eye end 106 is extended such that further bore 124 extends past tail housing 16. A pin (not shown) is inserted in further bore 124 to keep eye end 106 extended until attachment of Benthos device 14 (not shown in FIG. 4, but illustrated in FIG. 1). Once Benthos device 14 is attached, the pin may be removed as Benthos device 14 will serve to hold eye end 106 extended. When Benthos device 14 releases eye end 106, spring 120 expands away from shoulder 26a, retracting eye end 106 into slot 18 until faces 112a and 112b come to rest against base 22. In the preferred embodiment, rubber silencers 30 are affixed to base 22 such that faces 112a and 112b come to rest on silencers 30 thus attenuating any noise generated from faces 112a and 112b contacting base 22. Slots 126 extend from eye aperture 102 towards forward end 110, parallel to axis X--X on either side of middle portion 108 and allow water within bores 24, 26 and 28 to escape as eye end 106 retracts. Similarly, retainer ring 116 has flow apertures 116a allowing water to flow past retainer ring 116 as spring 120 expands and pushes retainer ring 116 through first bore 24.
Referring now to FIG. 5 there is shown an alternate embodiment of pull-down eye assembly 100' with spring 120' extended between and attached to middle portion 108' and forward end 110' As eye end 106' is extended from tail housing 16', spring 120' is stretched. When Benthos device 14 (not shown in FIG. 5) releases eye end 106', spring 120' contracts thus retracting eye end 106' into slot 18'. In the alternate embodiment of FIG. 5, second bore 26' extends to base 22' of slot 18'. Retainer ring 116' is held tight against stop 24b' by the action of spring 120'.
Pull-down eye assembly 100 of the present invention has many advantages over the prior art. The retraction of assembly 100 into tail housing 16, combined with exposed surface 104 of assembly 100 conforming to the shape of tail housing 16, eliminate turbulence caused by a protruding eye. Additionally, tail housing 16 and retracted assembly 100 are shaped to provide a non-turbulent flow over their surfaces, thus minimizing extraneous noise during BTV 10 testing. In the preferred embodiment, spring 120 is compressed as BTV 10 is hauled down below the surface. Once Benthos device 14 releases BTV 10, the expansion action of spring 120 automatically causes assembly 100 to quickly retract into tail housing 16. The use of slots 126 and flow apertures 116a provide adequate flow channels for water to escape from bores 24, 26 and 28 as assembly 100 retracts into tail housing 16, further decreasing retraction time. Rubber silencers 30 substantially quiet the contact of faces 112a and 112b against base 22. Finally, threaded bore 122 provides means for extracting assembly 100 from tail housing 16 in preparation of further BTV 10 tests.
What has thus been described is a non-turbulent, retractable pull-down eye assembly for use in hauling a BTV down to a release depth. The assembly is contained within the tail housing of the BTV. The exposed surface of the assembly when in the retracted position is shaped to conform to the shape of the BTV tail housing. When a BTV is to be hauled down, the assembly is extended from the tail housing. A hook and cable is attached through an eye in the extended portion of the assembly and the cable is winched to pull the BTV below the surface. When the BTV reaches the prescribed depth, an acoustic signal is used to release the hook. The assembly is spring loaded within the tail housing such that, upon release from the hook, the extended portion retracts back into the tail housing as the BTV rises to the surface.
Obviously many modifications and variations of the present invention in addition to the preferred and alternate embodiments may become apparent in light of the above teachings. For example, the spring can be replaced with any compressible or extensible material which will allow the extension of the pull-down eye and provide a retracting force when the eye is released. Further, the shape of the eye can be round, oval or any geometry corresponding to the hook used to haul down the BTV. Rather than providing slots for water escape, the clearance between the assembly and the tail housing can be increased allowing water to flow around the full assembly as it retracts into the tail housing. Also, the silencers can be mounted to either the assembly or the tail section and may be of any resilient material which will attenuate noise.
In light of the above, it is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US3897746 *||Jan 16, 1974||Aug 5, 1975||Us Navy||Submarine emergency towing rigging system|
|US4788927 *||Jan 29, 1988||Dec 6, 1988||Shell Western E&P, Inc.||Retractable towing shackle|
|US4890566 *||Mar 28, 1988||Jan 2, 1990||Morris John L||Retractable cleat|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US6304512 *||Nov 7, 2000||Oct 16, 2001||Mark A. Boys||Method and apparatus enabling remote release of hooks and hook assemblies to free fishing lures|
|US7530872 *||Feb 23, 2005||May 12, 2009||Keith Parten||Aquatic recreational system with retractable tow hook|
|U.S. Classification||114/249, 114/218, 441/7|
|International Classification||F16G17/00, B63B21/58|
|Cooperative Classification||F16G17/00, B63B21/58|
|European Classification||F16G17/00, B63B21/58|
|Jan 23, 1995||AS||Assignment|
Owner name: UNITED STATES OF AMERICA, THE, AS REPRESENTED BY T
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:NEDDERMAN, WILLIAM H., JR.;MEUNIER, ROBERT;REEL/FRAME:007331/0937
Effective date: 19941213
|May 25, 1999||REMI||Maintenance fee reminder mailed|
|Oct 31, 1999||LAPS||Lapse for failure to pay maintenance fees|
|Jan 11, 2000||FP||Expired due to failure to pay maintenance fee|
Effective date: 19991031